I have black panels on the sides of my car, I need something to make them dark again they have faded in the su?

I have a 2002 Pontiac Aztec that has black plastic like panels on the sides and bumpers, they have become faded by the sun and wear with time, I am looking for something that would make them darker and look newer and shiner, any suggestions? I have tried Armorel and Tire Shine but they always come off really quickly after apply'd!